Find a model for the Body Mass Index (BMI) of a person, given that BMI varies directly as a person's weight in pounds and inversely as the square of the person's height in inches. If a 7 ft tall person weighing 192 lb has a BMI of 19.13, how much weight would a 5 ft. 7 in. tall person weighing 128 lb need to gain or lose to have a BMI of 21? Write your answer as a positive value for weight gain or a negative value for weight loss. Round your answer to one decimal place. Answer Keypad Keyboard Shortcuts